Stress Echo for Ischemic Mitral Valve Surgery

Chronic ischaemic mitral regurgitation (IMR) is a frequent complication of coronary artery disease (CAD), and is associated with a poor prognosis and outcome. The role of concomitant mitral valve surgery for IMR in patients undergoing coronary artery bypass grafting (CABG) remains controversial. After myocardial infarction IMR is associated with poor outcome and prognosis with double mortality rates, it reduces survival following surgical or percutaneous revascularization. However, there is no consensus on the cut-off value of IMR. The thresholds to define severe secondary mitral regurgitation are need to be evaluated with regards to their impact on prognosis after mitral valve intervention. The European guidelines is defined effective regurgitant orifice (ERO)-0.2 cm2 and regurgitant volume (RV)-30ml, as the threshold for severe IMR, because of severe prognosis of this group. Whereas American guidelines are defined it as ERO-0.4 cm2 and RV-60ml, as it was no evidence to impact intervention on the IMR with ERO-0.2 cm2 and RV-30ml. Partly it's explained by the dynamic nature of the secondary MR. About 30% of patients from the group with non-massive regurgitation at rest, have dramatically increasing it during exercise. However, some patient have not changes or decreasing IMR during exercise and, probably, they have not such a negative impact on the hemodynamic by IMR. The pervious comparative studies, that were the base for recommendations did not differ the patients with and without changes IMR during exercise. The current guidelines doesn't support the stress echo (SE) exams before operation for assessing necessity in mitral valve operation. It's due to lack of information that prove of influence for survival after surgery depending on IMR dynamic parameters.

IMR study hypothesis: Stress echocardiography data, including ERO, RV, pulmonary pressure (PA) pressure, beta-lines - B-lines, contractile reserve, could be indications for mitral valve intervention in patient with CAD and chronic secondary mitral regurgitation, undergoing CABG. The patients of the group with non-massive (ERO-0.2 cm2 and RV-30ml) IMR have positive effect by mitral surgery if they have increasing IMR during exercise test. The group with massive IMR (ERO≥0.4 cm2 and RV≥60 ml) will be better according clinic, echo, stress echo results in comparison with non-massive non-operated subgroup.

Aim: To assess the value of stress echo testing for ischemic mitral surgery indication in patients undergoing CABG.

Inclusion criteria for all projects are:

1. Age > 18 years
2. IMR, ERO≥0.2 cm2 and RV≥30 ml.
3. Indication for CABG

Exclusion criteria for all projects are:

1. Unwillingness to give informed consent and to enter a regular follow-up program.
2. Contraindications for stress echo.

Methods and design:

1. In a prospective multicenter international randomized study, we will recruit patients whom CABG is planned.
2. Conventional transthoracic echo. Patients will include into two groups: Group 1 - "Non-massive IMR" - ERO-0.2-0.39 cm2, and RV-30-59ml. Group 2 - "Massive IMR" - ERO≥0.4 cm2 and RV≥60 ml.
3. Randomization of Group 1 (surgery/non-surgery).
4. Exercise stress echocardiography of all the patients (Group 1 and Group 2). regional wall motion abnormality (RWMA), ejection fraction (EF), end diastolic volume (EDV), end systolic volume (ESV), contractile reserve, B-lines, ERO, RV, PA pressure at rest and during stress.
5. 1-year clinical outcomes
6. 1-year transthoracic echo data.
7. 1-year stress echocardiography data.
8. 3-year clinical outcomes
9. 3-year transthoracic echo data.
10. 3-year stress echocardiography data. Primary end-points: death, myocardial infarction, new hospital readmission, heart transplant, ventricular assist device implantation, aborted sudden death, pulmonary oedema (MACE).

Secondary end-points: physical capacity (changes in Watts, minutes of stress echocardiography), EDV, left atrium volume, EF at rest and during SE, ERO, RV, PA pressure, B-lines, contractile reserve at rest and during exercise in comparison with pre-operative data.

Expected results. Group 1, CABG - subgroup, CABG+mitral surgery subgroup. It's expected the improvement of physical capacity (changes in Watts, minutes of stress echocardiography), EDV, left atrium volume, EF at rest and during SE, ERO, RV, PA pressure, B-lines, contractile reserve at rest and during exercise in comparison with pre-operative data in CABG+mitral surgery subgroup already in 1-year follow-up. It's expected the improvement of physical capacity (changes in Watts, minutes of stress echo), EDV, left atrium volume, EF at rest and during stress echo, ERO, RV, PA pressure, B-lines, contractile reserve at rest and during exercise in comparison with CABG-subgroup already in 1-year follow-up. It's expected that more pronounce changes will be in CABG+mitral surgery subgroup with previously increasing IMR. The worst results are expected in CABG-subgroup with previously increasing IMR during exercise. There will be clarified which parameters would be more correlate with the clinic improvement (contractile reserve, B-lines, ERO etc). We expected reduced MACE till 3 year in CABG+mitral surgery subgroup with increasing IMR in comparison with CABG-subgroup with increasing IMR.

Group 2, The group with massive IMR (ERO≥0.4 cm2 and RV≥60 ml) will be better according clinic, echo, stress echo results in comparison with CABG-subgroup with increasing IMR from group 1. There will be clarified which parameters would be more correlate with the clinic improvement (contractile reserve, B-lines, ERO etc).